v0.1.5: raw-bytes templates, per-user re-stamping, verify-single-sig New surface (FFI-backed): - TemplateFromBytes / EnvelopeFromBytes - Template.SetDocumentID / SetTitle / AddDescription / Description - Template.IsDataURL / DecodeDataURL - Envelope.VerifyParticipantSig Refreshed linux_amd64 + linux_arm64 static libraries.